Re: ring on PowerPC

Re: ring on PowerPC

[Wang, Baojun]

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On Wednesday 31 October 2007 13:05:16, Bai Shuwei wrote：
> Hi, everyone
>    As we know, the program on the X86 can run on the differnt ring(0, 1, 2,
> 3) and the linux kernel run in the ring 0 and user program in the ring 3.
> And now I want to know wether there is a simple mechanism on the PowerPC
> architecture? thx all!
>
> best regards!
>
> Buroc

powerpc has a machine state register(MSR), bit MSR_PR present the current 
privilege level, if msr & MSR_PR, then it's from user space, otherwise(msr & 
MSR_PR == 0) it's kernel space.

besides, the linux implementation only use ring0 and ring3 under i386, ring0 
is highest(kernel space), ring3 is lowest (userspace)

Wang
-- 
Wang, Baojun                                        Lanzhou University
Distributed & Embedded System Lab              http://dslab.lzu.edu.cn
School of Information Science and Engeneering        wangbj@lzu.edu.cn
Tianshui South Road 222. Lanzhou 730000                     .P.R.China
Tel:+86-931-8912025                                Fax:+86-931-8912022

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Re: ring on PowerPC

[Bai Shuwei]

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thanks all

On 10/31/07, Wang, Baojun <wangbj@lzu.edu.cn> wrote:
>
> On Wednesday 31 October 2007 13:05:16, Bai Shuwei wrote：
> > Hi, everyone
> >    As we know, the program on the X86 can run on the differnt ring(0, 1,
> 2,
> > 3) and the linux kernel run in the ring 0 and user program in the ring
> 3.
> > And now I want to know wether there is a simple mechanism on the PowerPC
> > architecture? thx all!
> >
> > best regards!
> >
> > Buroc
>
> powerpc has a machine state register(MSR), bit MSR_PR present the current
> privilege level, if msr & MSR_PR, then it's from user space, otherwise(msr
> &
> MSR_PR == 0) it's kernel space.
>
> besides, the linux implementation only use ring0 and ring3 under i386,
> ring0
> is highest(kernel space), ring3 is lowest (userspace)
>
> Wang
> --
> Wang, Baojun Lanzhou University
> Distributed & Embedded System Lab http://dslab.lzu.edu.cn
> School of Information Science and Engeneering wangbj@lzu.edu.cn
> Tianshui South Road 222. Lanzhou 730000 .P.R.China
> Tel:+86-931-8912025 Fax:+86-931-8912022
>
>


-- 

Add: Tianshui South Road 222, Lanzhou, P.R.China
Tel: +86-931-8912025
Zip Code: 730000
URL: oss.lzu.edu.cn
Email: baishuwei@gmail.com, buroc@126.com

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ring on PowerPC

[Bai Shuwei]

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Hi, everyone
   As we know, the program on the X86 can run on the differnt ring(0, 1, 2,
3) and the linux kernel run in the ring 0 and user program in the ring 3.
And now I want to know wether there is a simple mechanism on the PowerPC
architecture? thx all!

best regards!

Buroc

-- 

Add: Tianshui South Road 222, Lanzhou, P.R.China
Tel: +86-931-8912025
Zip Code: 730000
URL: oss.lzu.edu.cn
Email: baishuwei@gmail.com, buroc@126.com

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Re: ring on PowerPC

[Grant Likely]

On 10/30/07, Bai Shuwei <baishuwei@gmail.com> wrote:
> Hi, everyone
>    As we know, the program on the X86 can run on the differnt ring(0, 1, 2,
> 3) and the linux kernel run in the ring 0 and user program in the ring 3.
> And now I want to know wether there is a simple mechanism on the PowerPC
> architecture? thx all!

Powerpc has 2 privilege levels; user and supervisor.  The kernel runs
in supervisor mode, and user-space runs in user mode.

g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
grant.likely@secretlab.ca
(403) 399-0195

Re: ring on PowerPC

[Benjamin Herrenschmidt]

On Tue, 2007-10-30 at 23:18 -0600, Grant Likely wrote:
> On 10/30/07, Bai Shuwei <baishuwei@gmail.com> wrote:
> > Hi, everyone
> >    As we know, the program on the X86 can run on the differnt ring(0, 1, 2,
> > 3) and the linux kernel run in the ring 0 and user program in the ring 3.
> > And now I want to know wether there is a simple mechanism on the PowerPC
> > architecture? thx all!
> 
> Powerpc has 2 privilege levels; user and supervisor.  The kernel runs
> in supervisor mode, and user-space runs in user mode.

To be complete here, some implementations have 3 :-) Don't forget
hypervisor mode !

Ben.